Article Figures & Tables

Figures

A and C: Graphs demonstrating the correlation between capillary blood glucose determinations and glucose sensor readings. B and D: Bland-Altman plots showing the difference between capillary blood glucose measurements and simultaneous glucose sensor readings at different ambient glucose levels. The x-axis shows the mean of the two readings. The dashed line represents the 95% confidence limits of the differences between the two methods. A regression line is shown on each graph demonstrating that the mean differences between the methods is close to 0 and that there is no systematic difference between the methods at different ambient glucose levels. A and B depict independent capillary blood glucose levels that were measured while patients were wearing the glucose sensor, but that were not entered into the sensor for calibration. These were obtained during a preliminary phase of this study in a separate test population. C and D represent data from the current study population, comparing the capillary blood glucose values that were used for calibration for all of the tracings reported in this study. Values corresponding to tracings that were judged technically inadequate (see research design and methods) were excluded.

The midnight shift artifact. The graph shows continuous recording of glucose levels during 2 consecutive days. Note that after midnight there is a marked decrease in glucose values (short arrows) that could not be explained by physiological changes in blood glucose.

A–K: Continuous monitoring of glucose levels using the Minimed glucose sensor. Each graph shows a sample of the glucose values obtained from two sensors worn simultaneously by the same patient (x-axis: time; y-axis: sensor glucose values [in mg/dl]). •, corresponding capillary glucose values. Some graphs show <24-h recording because the portions considered technically uninterpretable were excluded. The graphs were obtained from six type 1 (B, C, E, H, I, and K) and three type 2 (D, F, and J) diabetic patients and two healthy volunteers (A and G). Some specific periods of clinically relevant discrepancy are indicated in rectangles.

A: Correlation between the data obtained simultaneously by two sensors on the same patient. Only technically acceptable tracings were included in this evaluation. The correlation coefficient was calculated by simple linear regression. B: Bland-Altman plot of the same data showing the difference between the two meter readings on the y-axis, and the mean of the two readings on the x-axis. The regression line is shown and indicates random differences between the two sensors at all levels. The dashed lines show the 95% confidence limits.